Pleural Space Infections: Microbiologic And Fluid Characteristics In 84 Patients

Background. The reported spectra of microorganisms responsible for empyema is varied, reflecting patient selection, host factors and microbiological methods for diagnosis. Patients and Methods. The medical and microbiological records of patients with positive cultures of pleural fluid, excluding Mycobacterium tuberculosis, were retrospectively analyzed in a teaching hospital over a 10-year period. Results. A total of 93 microorganisms were identified from the pleural fluid of 84 patients. The majority of bacterial isolates were Gram-positive organisms (67%), specifically viridans streptococci (19 isolates), Streptococcus pneumoniae (17), and Staphylococcus aureus (12), whereas Escherichia coli (7) was the most commonly encountered Gram-negative aerobic pathogen. Anaerobic isolates were only found in about 6% of cases. Overall, 63% of effusions had high pleural fluid adenosine deaminase levels. Medical comorbidity was common (69%), and 12% of patients with positive pleural fluid cultures responded to antibiotic therapy alone. Conclusions. Gram-positive aerobic microorganisms are still the most common isolated pathogens from pleural fluid in empyema. Adenosin deaminase activity is high in numerous parapneumonic effusions. Occasionally, a culture positive pleural effusion resolve without tube thoracostomy.